Simulation of Fibre Bragg Grating as Strain Sensor for Property Intrusion

This study will demonstrate a strain sensor based on the optical Fibre Bragg Grating (FBG) sensing technology as it is known to have stable and reliable wavelength and response as function of the applied strain. This kind of sensor can perform accurate measurements of small ground vibration and monitor seismic activity thanks to their high sensitivity to dynamic strains induced by acceleration variation which can use to prevent property intrusion or burglary. To understand the FBG sensor more, few of its characteristics such as strain, spectral reflectivity and bandwidth and their connection with the fibre grating length and refractive index is being studied. Keywords: Fibre Bragg Grating(FBG); strain sensor; strain; spectral reflectivity; bandwidth; fibre grating length; refractive index; safety; property intrusion.

Efficient land use based on remote sensing data

The goal -is to explore ways of using Earth remote sensing data for efficient land use. Methods - detailed information on current location of certain types of agricultural crops in the study areas has been summarized, which opens up opportunities for the effective use of cultivated areas. It was revealed that the basis of the principle of the method under consideration is the relationship between the state and structure of vegetation types with its reflective ability. It has been determined that information on the spectral reflective property of the vegetation cover in the future can help replace more laborious methods of laboratory analysis. For classification of farmland, satellite images of medium spatial resolution with a combination of channels in natural colors were selected. Results - a method for identifying agricultural plants by classification according to the maximum likelihood algorithm was considered. The commonly used complexes of geoinformation software products with modules for special image processing allow displaying indicators in the form of raster images. It is shown that the use of Earth remote sensing data is the most relevant solution in the field of crop recognition and makes it possible to simplify the implementation of such types of work as the analysis of the intensity of land use, the assessment of the degree of pollution with weeds and determination of crop productivity. Conclusions - the research results given in the article indicate that timely information on the current location of certain types of agricultural crops in the studied territories significantly simplifies the implementation of the tasks and increases the resource potential of agricultural lands. In turn, the timing of the survey and the state of environment affect the spectral reflectivity of vegetation.

Modulated Noncollinear Optical Parametric Amplifier Output Induced by Stimulated Raman Scattering

We studied spectra of the amplified signal from a noncollinear optical parametric amplifier (NOPA) based on a Ti:sapphire laser and BBO crystal gain medium. The signal shows characteristic structures with periodic intensity variations in the signal during the parametric amplification processes in a BBO crystal. This phenomenon is attributed to the stimulated Raman process excited by the pump pulse affected by the phase-matching condition of four-wave mixing. The effect of this stimulated Raman process on optical parametric amplification and on final pulse compression of the signal was analyzed. The results demonstrate that caution must be taken when constructing a NOPA. Specifically, great care must be taken not to use mirrors with non-uniform spectral reflectivity for obtaining a stable pulse in terms of both temporal and spectral shapes.

Mapping soil organic carbon under erosion processes using remote sensing

This study aimed to map soil organic carbon under erosion processes on an arable field in the Republic of Bashkortostan (Russia). To estimate the spatial distribution of organic carbon in the Haplic Chernozem topsoil, we applied Sentinel-2A satellite data and the linear regression method. We used 13 satellite bands and 15 calculated spectral indices for regression modelling. A regression model with an average prediction level has been created (R2 = 0.58, RMSE = 0.56, RPD = 1.61). Based on the regression model, cartographic materials for organic carbon content have been created. Water flows and erosion processes were determined using the calculated Flow Accumulation model. The relationship between organic carbon, biological activity, and erosion conditions is shown. The 13C-NMR spectroscopy method was used to estimate the content and nature of humic substances of different soil samples. Based on the 213C-NMR analysis, a correlation was established with the spectral reflectivity of eroded and non-eroded soils. It was revealed that the effect of soil organic carbon on spectral reflectivity depends not only on the quantity but also on the quality of humic substances and soil formation conditions.

Pan-Arctic and regional trends of reflectance, clouds and fluxes: implications for Arctic Amplification

<p>It is now well known that the sea ice extent in the Artic has been shrinking in the past three decades in the period known as the Arctic Amplification. A simple assumption would be that if the sea ice extent has been reduced, then the spectral reflectance at the top of the atmosphere - R<sub>TOA</sub> - would have also decreased across the Arctic. On the other hand, Arctic reflectivity also largely depends on the presence of clouds, shielding the underlying surface, and on changes of their optical and physical properties. Thus, the assessment of trends of spectral reflectivity and cloud properties are essential to understand those forcings and feedbacks considered drivers of Arctic Amplification as well as the interactions between the components of the Arctic cryosphere. In the reported study we observationally tackle the stated problem investigating changes of R<sub>TOA</sub> at selected wavelengths making use of spaceborne measurements of the Global Ozone Monitoring Experiment (GOME onboard ERS-2 and MetOp A/B/C) and of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY onboard Envisat) for the period 1995-2018. We complement this record with cloud properties and fluxes at top of the atmosphere and at the surface, inferred from measurements of the post-meridiem orbits of the Advanced Very High Resolution Radiometer (AVHRR onboard POES). Although the Pan-Arctic reflectivity has decreased, the analysis of regional trends shows distinct areas where the reflectivity trends diverge. While darkening areas can be attributed to seasonal sea ice decline, an increase of Arctic brightness over sea ice free regions can be largely attributed to changes in the optical properties of clouds. While the multiyear mean of the radiative forcing by clouds points to a TOA cooling and a surface warming, its trends exhibit opposite tendencies. In the last two decades, the cloud radiative effect at TOA is expected to warm the lower latitudes (below 75 N) and to cool the circumpolar belt, while an opposite trend at BOA, amounting to 5 W m<sup>-2 </sup>per decade, cools the lower Arctic latitudes and warms the permanent sea ice region, this effect being more pronounced in spring months (April to June) than in summer months (July to September).</p>

Variations in spectral reflectivity and vertical cloud structure of Jupiter’s Great Red Spot

<p>The Great Red Spot (GRS) of Jupiter is a large anticyclonic vortex present in the Jovian atmosphere. First observed in the XVII century, it is almost constantly located at 22°S and it is arguably one of the main atmospheric phenomena in the Solar System. Despite having been widely studied, the nature of the chromophore species that provide its characteristic colour to the GRS’s upper clouds and hazes is still unclear, as well as its creation and destruction mechanisms.</p><p>In this work we have analysed images provided by the Hubble Space Telescope’s Wide Field Camera 3 between 2015 and 2019, with a spectral coverage from the ultraviolet to the near infrared, including two methane absorption bands. These images have undergone a photometric process of cross calibration, ensuring a consistent correlation among the images corresponding to different visits and years. From such calibrated images, we have obtained the spectral reflectivity of the GRS and its surroundings, with particular emphasis on a few, dynamically interesting regions.</p><p>We used the NEMESIS radiative transfer suite to retrieve the main atmospheric parameters (particle vertical and size distributions, refractive indices…) that are able to explain the observed spectral reflectivity of the selected regions. Here we report the spatial and temporal variations on such parameters and their implications on the GRS overall dynamics.</p>

Study on loss processes in solar cells

Determining heat sources for solar cells is essential to avoid energy loss, which in turn causes the efficiency of solar cells to decrease and therefore, the loss processes have a significant impact on solar conversion. This paper presents a study of intrinsic and exogenous losses in solar cells, identification of the resulting energy loss at different temperatures, and discusses the impact of exogenous and spectral reflectivity on solar cell performance. The results show an increase in thermal loss with an increase in temperature, which in turn leads to a decrease in the efficiency of solar cells. Also explained that the external radiate efficiency, spectral reflectance and operating temperature significantly affect the loss processes. The efficiency of the cell begins to decrease with the decrease of its external radiate efficiency.

Variations in spectral reflectivity and vertical cloud structure of Jupiter’s Great Red Spot

<p>The Great Red Spot (GRS) of Jupiter is a large anticyclonic vortex present in the Jovian atmosphere. First observed in the XVII century, it is almost constantly located at 22°S. Since its discovery it has gradually decreased in size at an average rate of 170 km/year in longitude and 60 km/year in latitude. The nature of the chromophore species that provide its characteristic color to the GRS’s upper clouds and hazes is still largely unknown, as well as its creation and destruction mechanisms. During year 2019, the GRS began to lose some of this reddish material as a consequence of the interaction with other vortices present in nearby latitudes, raising serious doubts about its possible disappearance (Sánchez-Lavega et al., 2019).</p> <p>In this work we have analyzed images provided by the Hubble Space Telescope between 2015 and 2019, with a spectral coverage from the ultraviolet to the near infrared, including some methane absorption bands of different depths. These images have been calibrated in absolute reflectivity, and from them we have obtained the spectral variations in brightness that occur in different dynamically interesting regions of the GRS and its surroundings.</p> <p>The spectral reflectivity of the studied regions over the mentioned years has been analyzed using the NEMESIS radiative transfer code (Irwin et al., 2008). In this way it has been possible to retrieve the main features playing a key role in the spectral reflectivity of GRS’s upper clouds and hazes, such as particle size distribution, refractive indexes and optical thickness. At the same time, this analysis has provided the vertical distribution of particles for pressure levels above 1 bar, allowing a comparative study of its evolution over recent years.</p> <p><strong>References</strong></p> <p>-Irwin, P. G. J., Teanby, N. A., de Kok, R., Fletcher, L. N., Howett, C. J. A., Tsang, C. C. C., . . . Parrish, P. D. (2008, April). The NEMESIS planetary atmosphere radiative transfer and retrieval tool. <em>Journal of Quant. Spec. and Radiative Transfer</em>, 109, 1136-1150. doi: 10.1016/j.jqsrt.2007.11.006</p> <p>- Sánchez-Lavega, A., Iñurrigarro, P., Anguiano-Arteaga, A., Garcia-Melendo, E., Legarreta, J., Hueso, R., Sanz-Requena, J.F., Pérez-Hoyos, S.,  Mendikoa, I., Soria, M., Rojas, J.F. Jupiter’s Great Red Spot threatened along 2019 by strong interactions with close anticyclones, AGU Fall Meeting, P44A-01, San Francisco, 12 December 2019</p>